JP2010512919A - Method for influencing and / or detecting magnetic particles in the working area to be examined - Google Patents

Abstract

  Disclosed are methods and mechanisms for influencing and / or detecting magnetic particles in the area of action to be examined. The method includes generating, by the selection means, a selected magnetic field having a spatial pattern of magnetic field strength such that a first subzone having a low magnetic field strength and a second subzone having a higher magnetic field strength are formed in the working region. Changing the spatial position of the two sub-zones in the working region so that the magnetization of the magnetic particles changes locally by the driving magnetic field generated by the driving means, and the receiving means by the first and second Obtaining a signal dependent on the magnetization of the working area affected by a change in the spatial position of the subzone, wherein the selection means and / or the driving means and / or the receiving means are in the acquisition and / or working area Configured to be at least partially movable with respect to the object to be examined during a change in the spatial position of the two sub-zones. .

Description

  The present invention relates to a method for influencing and / or detecting magnetic particles in a working area to be examined. Furthermore, the invention relates to a mechanism for influencing and / or detecting magnetic particles in the working area to be examined and the use of such a mechanism.

  A method for influencing and / or detecting magnetic particles is known from DE 101 51 778 A1. In the case of the method described in the above publication, first of all the magnetic field strength such that a first subzone having a relatively low magnetic field strength and a second subzone having a relatively high magnetic field strength are formed in the examination zone. A magnetic field having a spatial distribution of The spatial position of the subzones in the examination zone is shifted, thereby changing the magnetization of the particles in the examination zone locally. Signals depending on the magnetization in the examination zone affected by the shift of the spatial position of the subzone are recorded and information on the spatial distribution of the magnetic particles in the examination zone is obtained from these signals, thereby An image of the zone can be formed. Such a mechanism and such a method do not cause any damage in a non-destructive manner, with high spatial resolution both near and away from the surface to be examined, It has the advantage that it can be used to test any test object, such as the human body.

  There is always a need to expand the field of possible applications of such known mechanisms by reducing the number of demands on the required space or on the weight of the mechanism or part thereof.

  Accordingly, it is an object of the present invention to provide a method that gives a higher degree of flexibility over known methods.

The object is a method for influencing and / or detecting magnetic particles in the working area of the test object,
-Generating, by the selection means, a selected magnetic field having a spatial pattern of magnetic field strength such that a first subzone having a low magnetic field strength and a second subzone having a higher magnetic field strength are formed in the working area;
-Changing the spatial position of the two sub-zones in the working region by means of a drive magnetic field generated by the drive means so that the magnetization of the magnetic particles changes locally;
Obtaining, by the receiving means, a signal dependent on the magnetization in the working area affected by a change in the spatial position of the first and second subzones;
And the selection means and / or the drive means and / or the reception means are at least partially movable relative to the object to be examined during a change in the spatial position of the two subzones in the acquisition and / or working area Achieved by the method.

  The advantage of such a method is that it is possible to achieve higher flexibility in the application of magnetic particle imaging methods. For example, the cutting member of the (medical) cutting device can be observed or the method of the invention is carried out during movement of the cutting member.

  According to a preferred embodiment of the invention, the movement of at least part of the selection means and / or drive means and / or reception means is traced. This advantageously allows the action area to be continuously scanned when there is a movement of the action area relative to the examination object.

  Furthermore, according to the present invention, the tracing can be performed optically and / or mechanically by signal processing of the acquired signals and / or movement of at least part of the selection means and / or drive means and / or reception means. And / or preferably by electrical tracing. This advantageously makes it possible to track or trace the relative movement of the working area and the object to be examined very flexibly.

The invention further provides a mechanism for influencing and / or detecting magnetic particles in the area of action to be examined,
A selection means for generating a selected magnetic field having a spatial pattern of magnetic field strength such that a first subzone having a low magnetic field strength and a second subzone having a higher magnetic field strength are formed;
A driving means for changing the spatial position of the two subzones in the working region by a driving magnetic field so that the magnetization of the magnetic particles changes locally;
Receiving means for obtaining a signal dependent on the magnetization of the working area affected by the change in the spatial position of the first and second subzones;
And the selection means and / or the drive means and / or the reception means are configured to be at least partially movable relative to the object to be examined.

  The mechanism according to the invention advantageously makes it possible to provide a continuous measurement of the position and / or distribution of the magnetic particles in the working area while the working area moves relative to the object to be examined. The movement can also be carried out, for example, by mechanically moving a permanent magnet that is part of the selection means.

  According to a preferred embodiment of the invention, the mechanism has tracing means for tracing the movement of the working area relative to the object to be examined. This advantageously allows the volume to be examined to be expanded without the need for a large magnetic field generator such as a heavy coil. This offers the possibility of providing the mechanism of the present invention that is lightweight and very flexible.

  According to a preferred embodiment of the present invention, the tracing means optically process at least part of the selection means and / or the drive means and / or the reception means by signal processing of the acquired signals and / or. And / or by mechanical and / or electrical tracing. This makes it possible to apply many different tracing or tracking techniques in order to allow movement of the working area relative to the object to be examined.

  According to another preferred embodiment of the invention, the mechanism comprises a medical device comprising at least a part of selection means and / or drive means and / or reception means configured to be movable relative to the examination subject. Have This makes it possible to measure the distribution of magnetic particles even when a medical device (such as a scalpel or scanning head) moves.

  According to another preferred embodiment of the invention, the medical device has a ceramic part, in particular a blade. This makes it possible to use a material in at least a part of the medical device that does not cause distortion of the magnetic field so strong that it prevents the application of the method of the invention or the use of the mechanism of the invention.

  The invention further relates to the use of the inventive mechanism inside a vehicle, in particular an ambulance. This offers the potential for fairly high resolution imaging techniques for in-vehicle diagnostic purposes. This is particularly useful for stroke patients where early diagnosis is important. This is because the selection of the appropriate drug is highly dependent on the type of stroke. In the case of hemorrhagic stroke, anticoagulants are contraindicated, but they are very beneficial in the case of embolic stroke. The earlier a diagnosis can be made, the greater the chance that the patient will survive. The mechanism of the invention used inside the vehicle, particularly for the diagnosis of stroke patients, is preferably configured such that all its components fit around the patient's head.

  These and other objects, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. The description is given for the sake of example only and does not limit the scope of the invention. The reference figures quoted below refer to the attached drawings.

FIG. 2 shows a mechanism according to the invention for carrying out the method according to the invention. The figure which shows the example of the magnetic force line pattern produced | generated by the mechanism by this invention The figure which shows the different example which traces the movement of the action | operation area | region with respect to a test object.

  Although the invention has been described with respect to particular embodiments and with reference to certain drawings, the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the components may be exaggerated and not drawn on scale for convenience of description.

  Indefinite or definite articles such as “a”, “an”, “the” are used when referring to a singular noun, and this includes the plural of that noun unless specifically stated otherwise.

  Furthermore, the terms first, second, third, etc. in this description and in the claims are used to distinguish similar components and are not necessarily used to describe a sequential or sequential order. It has not been.

  The terms so used can be interchanged under appropriate circumstances, and the embodiments of the invention described herein can operate in a different sequence than those described or illustrated herein. It should be understood.

  The words top, bottom, top, bottom, etc. in this description and in the claims are used for descriptive purposes and are not necessarily used to describe relative positions. The terms so used are interchangeable under appropriate circumstances, and the embodiments of the invention described herein are operable in other orientations than those described or illustrated herein. It should be understood that there is.

  The word “comprising” used in this description and in the claims should not be construed as limited to the means listed thereafter; it does not exclude other elements or steps. It should be noted that. Thus, the scope of the expression “apparatus with means A and B” should not be limited to apparatuses containing only components A and B. This means that for the present invention, the only relevant components of the device are A and B.

  FIG. 1 illustrates any object to be examined by a mechanism 10 according to the present invention. Reference numeral 350 in FIG. 1 indicates a patient placed in the patient table, in this case a human or animal, and only a portion of the top of the table is shown. Prior to application of the method according to the invention, magnetic particles 100 (not shown in FIG. 1) are placed in the working area 300 of the mechanism 10 according to the invention. In particular, prior to therapeutic and / or diagnostic treatment of, for example, a tumor, the magnetic particles 100 are applied to the active region 300 by a liquid (not shown) that includes, for example, magnetic particles 100 that are injected into the body of a patient 350. Positioned.

  As an example of an embodiment of the present invention, a mechanism 10 having a plurality of coils forming the selection means 210 is shown in FIG. The range of the selection means defines an action area 300, also called an examination area 300. For example, the selection unit 210 is disposed above and below the target 350. For example, the selection means 210 has a first coil pair 210 ′, 210 ″, each coil having two windings 210 ′ and 210 ″ configured identically, these windings. Are arranged coaxially above and below the patient 350 and are traversed in particular in opposite directions by equal currents. Both first coil pairs 210 ′, 210 ″ are referred to below as selection means 210. Preferably a direct current is used in this case. The selection means 210 generally generates a selection magnetic field 211 that is a gradient magnetic field represented in FIG. The selection magnetic field 211 has a substantially constant gradient in the direction of the (eg vertical) axis of the coil pair of the selection means 210 and reaches a zero value at a point on this axis. Starting from this point without a magnetic field (not shown separately in FIG. 2), as the distance from the point without a magnetic field increases, the magnetic field strength of the selected magnetic field 211 increases in all three spatial directions. In the first subzone 301 or region 301 indicated by the broken line around the point where there is no magnetic field, the magnetic field strength is so small that the magnetization of the magnetic particles 100 existing in the first subzone 301 is not saturated, on the other hand (outside of the region 301 The magnetization of the magnetic particle 100 present in the second subzone 302 is in a saturated state. The field-free point or first subzone 301 of the working region 300 is preferably a spatially coherent region, which can be a point-like region, a linear region or a flat region. In the second subzone 302 (ie, the rest of the active region 300 outside the first subzone 301), the magnetic field strength is strong enough to keep the magnetic particles 100 in saturation. By changing the position of the two sub-zones 301, 302 in the working area 300, the (overall) magnetization in the working area 300 is changed. By measuring the magnetization 300 or physical parameters in the working region affected by the magnetization, it is possible to obtain information about the spatial distribution of the magnetic particles 100 in the working region.

  If another magnetic field, referred to below as the drive field 221, is superimposed on the selection field 210 (or gradient field 210) in the working region 300, the first subzone 301 is in the direction of this drive field 221 in the second subzone 302. Shifted with respect to. As the strength of the driving magnetic field 221 increases, the degree of this shift increases. When the superimposed drive magnetic field 221 changes over time, the position of the first subzone 301 changes in time and space accordingly. It is advantageous to receive and detect signals from the magnetic particles 100 located in the first subzone 301 in a different frequency band (shifted to a higher frequency) than the frequency band of the drive magnetic field 221 variation. This is possible because the harmonic frequency component of the frequency of the drive magnetic field 221 is caused by a change in magnetization of the magnetic particles 100 in the working region 300 as a result of the non-linearity of the magnetization characteristics due to the saturation effect.

  In order to generate a drive magnetic field 221 for any given direction of space, three drive coil pairs are provided, ie, first drive coil pair 220 ′, second, hereinafter referred to as drive means 220. Drive coil pair 220 ″ and third drive coil pair 220 ′ ″. For example, the first drive coil pair 220 ′ generates a component of the drive magnetic field 221 that extends in a given direction, ie, for example, vertically. For this purpose, the windings of the first drive coil pair 220 ′ are traversed in the same direction by equal currents. The two drive coil pairs 220 ″, 220 ′ ″ are components of the drive magnetic field 221 that extend in different directions in the space, for example horizontally in the longitudinal direction of the working area 300 (or the patient 350) and in a direction perpendicular thereto. Is configured to generate If Helmholtz type second and third drive coil pairs 220 ″, 220 ′ ″ are used for this purpose, these drive coil pairs are respectively to the left and right of the treatment area or before and after this area. Must be placed. This affects the accessibility of the working area 300 or the treatment area 300. Accordingly, the second and / or third drive field coil pairs or coils 220 ″, 220 ′ ″ are also placed above and below the working area 300, so that their winding structure is the first drive Must be different from that of coil pair 220 '. However, this type of coil is an open magnet (with radio frequency (RF) drive coil pairs positioned above and below the treatment area, which can generate a temporally variable horizontal magnetic field ( Known from the field of magnetic resonance apparatus with open MRI). Thus, the structure of such a coil need not be described in further detail here.

  The mechanism 10 according to the invention further comprises receiving means 230, which is only schematically shown in FIG. The receiving means 230 usually has a coil that can detect a signal induced by the magnetization pattern of the magnetic particles 100 in the working region 300. However, this type of coil is known from the field of magnetic resonance devices where, for example, radio frequency (RF) coil pairs are located around the active region 300 so that they have the highest possible signal-to-noise ratio. Thus, the structure of such a coil need not be described in further detail here.

  Such a mechanism and such a method for detecting magnetic particles is known from DE 10151 778, the content of which is incorporated here in its entirety.

  Another mechanism 10 for performing magnetic particle imaging is known from WO 2006/067692 A2, the contents of which are hereby incorporated by reference in its entirety. This document discloses the use of the whole concept of magnetic particle imaging by transferring at least part of the selection means 210, the drive means 220 and / or the reception means 230 to a handheld device such as a medical device. .

  In one aspect of the invention, a portion of the mechanism 10 is transferred to a handheld device or mobile device that is movable relative to the test object 350. In accordance with the method and mechanism 10 of the present invention, it is possible to determine the movement of the working area 300 relative to the test object 350 by tracking or tracing the movement of the mobile device or handheld device. This can greatly reduce the equipment required in the mechanism 10 that affects and / or detects magnetic particles according to magnetic particle imaging methods. If the movement of the first subzone 301 in the working area 300 by the drive means 220 covers only a relatively small volume, for example several tens of cubic centimeters, and there is a need to scan a larger volume, It is possible to use a magnetic field generating means. It is very difficult, if not impossible, to incorporate such auxiliary magnetic field generating means into a handheld device. Thus, according to one aspect of the invention, it is proposed to use handheld device movement to expand the volume to be scanned. In order to connect different sized regions of the working area 300 that can be scanned at once (or at least fairly quickly), the mechanism 10 of the present invention preferably provides movement of the moving parts of the mechanism 10, such as the handheld part. It has tracing means 250 for tracing.

  In FIG. 3, a different example or possibility of tracing the movement M of the working area 300 relative to the inspection object 350 is schematically shown. The movement M of the working area 300 corresponds to the movement M of the mechanism 10 or at least a part thereof, for example a handheld device including at least a part of the selection means 210, the driving means 220 and / or the receiving means 230. The position of the moved working area 300 and the moved mechanism 10 or part of the mechanism 10 is indicated by the small dashed lines in FIG.

  Several possibilities exist for determining the movement M. According to one aspect of the invention, this can be done by a tracing means 250, such as an accelerometer (not shown), for example determining the acceleration and deceleration of a part of the mechanism 10, such tracing means. 250 is preferably mounted on a handheld device. Furthermore, the movement can be traced by optical means such as, for example, a laser beam (indicated schematically by a housing and arrows outside the tracing means 250 and detecting the position of the mechanism 10 or a part thereof. To do). Similarly, a mechanical embodiment of the tracing means 250 can be provided, for example mechanical transmission of the movement M.

  According to another possibility, the movement M can be detected by reconstructing the volume to be scanned with its already scanned area. This can be understood as follows: the working area 300 provides an overlapping area 300 'of the working area 300 before the movement is performed and the working area 300 after the movement is performed. To be moved a sufficiently small distance. For example, if the assumption that the distribution of the magnetic particles 100 did not change dramatically while the movement was performed is correct, the information of the overlap region 300 ′ may be, for example, an image of the scanned region, It can be used with appropriate signal processing to expand the scannable area by means of adding a new volume (which was not covered at the position of the working area 300 before the movement M).

  In accordance with the present invention, one or more different tracing methods can be used to determine the position of the mechanism 10 or part of the mechanism after the movement M. Furthermore, for long range movements only or preferably one type of tracing means 250 is used, for short range movements only or preferably for short ranges and relatively fast movements, for example. Different possibilities of tracing can be combined so that other types of tracing means 250 are used, such as tracing means using only signal processing. The recorded signal of the extended area, which is an interaction with the moving active area 300, is used to form a well-space-resolved tomographic image of, for example, a part of the patient's body. Can do. In addition, the recorded signal can be further expressed optically or acoustically, allowing a quick determination of the localized particle concentration. This allows for effective detection of special body tissues or other objects over a relatively large volume, such as sentinel lymph node detection.

  Furthermore, according to another aspect of the invention, a medical device (not shown) such as a surgical device may comprise at least a part of the receiving means 230 of the mechanism 10 for magnetic particle imaging. As a result, the presence or absence of the magnetic particles 100 around the medical device can be directly detected and specified. For example, it is advantageous to provide a medical device that uses ceramic at least in part, for example, the portion of the medical device that forms the blade can be provided using ceramic. The receiving means 230 (for example in the form of a receiving coil) or a part thereof can be advantageously positioned in the vicinity of the ceramic part, so that, for example, when the amplifier is integrated in a medical device, depending on the applied magnetic field 221 The generated harmonics can be detected. The drive magnetic field 221 can be generated by a source on the medical device (eg, in a shaft) or by an external source. In the case of external generation, the medical device does not require a cable connection and can be powered by a battery. In order to improve the localization of the magnetic particles 100, a selected magnetic field generator (eg a permanent magnet) as part of the selection means 210 is part of a medical device, eg one magnetic pole of the selected magnetic field generator. It can be used completely or partially. This selective magnetic field generator on the medical device can be configured to be mechanically adjustable to move the sensing spot to the desired position relative to the device, which is the intended intervention. In the case of the best.

  According to yet another aspect of the present invention, the mechanism 10 of the present invention is used inside a vehicle (not shown), particularly an ambulance. The mechanism 10 of the present invention used inside the vehicle, particularly for the diagnosis of stroke patients, is preferably configured so that all components are fitted around the patient's head. . According to this aspect of the invention, the permanent magnets as part of the selection means 210 can be configured to be mechanically moved so that they move the working area 300. The amplitude of the drive field in this case is preferably limited to a fairly low value, for example less than about 20 mT. Due to the fact that the required spatial resolution is not very high, the gradient of the selected magnetic field can be very low, for example less than about 1 Tesla per meter. This allows a reasonable field of view despite the low drive field amplitude. In particular, the static magnetic field of the selected magnetic field generator as part of the selection means 210 and the drive magnetic field 221 of the drive means 220 are actively shielded to minimize interference with other equipment in the vehicle. In order to reduce artifacts in acquired images, ambulances are equipped with radio frequency shielding material that can be placed inside the vehicle door.

Claims (12)

A method for influencing and / or detecting magnetic particles in a working area to be inspected, comprising:
Generating a selected magnetic field having a spatial pattern of magnetic field strength such that a first sub-zone having a low magnetic field strength and a second sub-zone having a higher magnetic field strength are formed in the working region by the selection means;
Changing the spatial position of the two sub-zones in the working region such that the magnetization of the magnetic particles is locally changed by the driving magnetic field generated by the driving means;
Obtaining by the receiving means a signal dependent on the magnetization of the working area affected by the change in the spatial position of the first and second sub-zones;
The selection means and / or the driving means and / or the receiving means for the inspection object during the acquisition and / or during the change of the spatial position of the two sub-zones in the working area Configured to be at least partially movable.   The method according to claim 1, wherein movement of at least part of the selection means and / or the drive means and / or the reception means is traced.   The method of claim 2, wherein the tracing is performed by signal processing of the acquired signal.   The tracing is performed by optically and / or mechanically and / or electrically tracing the movement of at least part of the selection means and / or the drive means and / or the reception means. The method according to claim 2. A mechanism for influencing and / or detecting magnetic particles in the region of action to be examined,
Selection means for generating a selected magnetic field having a spatial pattern of magnetic field strength such that a first subzone having a low magnetic field strength and a second subzone having a higher magnetic field strength are formed in the working area;
Driving means for changing the spatial positions of the two sub-zones in the working region so that the magnetization of the magnetic particles is locally changed by a driving magnetic field;
Receiving means for obtaining a signal dependent on the magnetization of the working region affected by the change in the spatial position of the first and second subzones;
And the selection means and / or the drive means and / or the receiving means are configured to be at least partially movable with respect to the test object.   6. A mechanism according to claim 5, wherein the mechanism comprises tracing means for tracing the movement.   The mechanism according to claim 6, wherein the tracing means is realized by signal processing of the acquired signal.   The tracing means is realized by optically and / or mechanically and / or electrically tracing the movement of at least part of the selection means and / or the driving means and / or the receiving means. The mechanism according to claim 6.   The mechanism according to claim 8, wherein the tracing means includes an acceleration sensor.   The said mechanism has a medical apparatus which has at least one part of the said selection means and / or the said drive means and / or the said reception means comprised so that a movement with respect to the said test object is possible. The mechanism described in.   11. A mechanism according to claim 10, wherein the medical device has a ceramic part, in particular a blade.   Use of the mechanism according to claim 5 especially inside a vehicle such as an ambulance.

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